Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Mime-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=UTF-8
Date:   Mon, 10 Jul 2023 18:50:26 +0200
Cc:     <linux-wireless@vger.kernel.org>
Subject: Re: [regression] STP on 80211s is broken in 6.4-rc4
From:   "Nicolas Escande" <nico.escande@gmail.com>
To:     "Linux regressions mailing list" <regressions@lists.linux.dev>,
        "Bagas Sanjaya" <bagasdotme@gmail.com>, <nbd@nbd.name>,
        =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>,
        "Kalle Valo" <kvalo@kernel.org>,
        "Johannes Berg" <johannes.berg@intel.com>
Message-Id: <CTYNAK10A6AJ.1I4W9V78VG1NB@syracuse>
References: <CT5GNZSK28AI.2K6M69OXM9RW5@syracuse>
 <ZIQbs0wqdRh7c0Kx@debian.me>
 <a9d02800-2cd6-a27b-7998-4c97cf2eb692@leemhuis.info>
 <CTDWJJDKSYYD.XBG1CAZB3A5W@syracuse>
 <809500b6-4eec-7a5e-5930-00e7eeebcc5e@leemhuis.info>
In-Reply-To: <809500b6-4eec-7a5e-5930-00e7eeebcc5e@leemhuis.info>
Precedence: bulk

On Mon Jul 10, 2023 at 1:32 PM CEST, Linux regression tracking (Thorsten Le=
emhuis) wrote:
> On 16.06.23 09:45, Nicolas Escande wrote:
> > On Thu Jun 15, 2023 at 2:54 PM CEST, Linux regression tracking (Thorste=
n Leemhuis) wrote:
> >> On 10.06.23 08:44, Bagas Sanjaya wrote:
> >>> On Tue, Jun 06, 2023 at 12:55:57PM +0200, Nicolas Escande wrote:
> >>>>
> >>>> As user of the mesh part of mac80211 on multiple products at work le=
t me say
> >>>> thank you for all the work you do on wifi, especially on 80211s, and=
 especially
> >>>> the recent improvements you made for mesh fast RX/TX & cross vendor =
AMSDU compat
> >>>>
> >>>> We upgraded our kernel from an older (5.15) to a newer 6.4. The prob=
lem is STP=20
> >>>> doesn't work anymore and alas we use it for now (for the better or w=
orse).
> >>>>
> >>>> What I gathered so far from my setup:
> >>>>  - we use ath9k & ath10k
> >>>>  - in my case STP frames are received as regular packet and not as a=
msdu
> >>>>  - the received packets have a wrong length of 44 in tcpdump
> >>>>    (instead of 38 with our previous kernel)
> >>>>  - llc_fixup_skb() tries to pull some 41 bytes out of a 35 bytes pac=
ket
> >>>>    this makes llc_rcv() discard the frames & breaks STP
> >>>>
> >>>> >From bisecting the culprit seems to be 986e43b19ae9176093da35e0a844=
e65c8bf9ede7
> >>>> (wifi: mac80211: fix receiving A-MSDU frames on mesh interfaces)
> >>>>
> >>>> I guess that your changes to handle both ampdu subframes & normal fr=
ames in the
> >>>> same datapath ends up putting a wrong skb->len for STP (multicast) f=
rames ?
> >>>> Honestly I don't understand enough of the 80211 internals & spec to =
pinpoint the
> >>>> exact problem.
> >>>>
> >>>> It seems this change was already in the 6.3 kernel so I guess someon=
e should
> >>>> have seen it before (but I didn't find anything..) ? Maybe I missed =
something...
> >>>>
> >>>> Anyway I'm happy to provide more info or try anything you throw at m=
e.
> >> [...]
> >> Hmmm, Felix did not reply. But let's ignore that for now.
> >=20
> > I haven't seen mails from felix on the list for a few days, I'm guessin=
g he's
> > unavailable for now but I'll hapilly wait.
>
> Still no progress. Hmmm. Are you still okay with that? I've seen no
> other reports about this, so waiting is somewhat (albeit not completely)
> fine for me if it is for you.
I'm not so surprised no one else reported it, using STP on wifi (and 802.11=
s) is
not a really common thing to do, to be honest (and STP on wifi is unreliabl=
e).
Even though some openwrt guys do it for sure, I'm guessing their kernel ver=
sion
is lagging behind...
>
> But in any case it might be good if you could recheck 6.5-rc1.
Testing on 6.5 as a whole won't be as easy for me as testing a single patch=
 on
top of 6.4. I'll do my best to try but from what I saw nothing got merged t=
hat
would even remotely help me on this issue.=20

I am not loosing hope that Felix or someone that understands this stuff bet=
ter
finds the time to look into this. I'm guessing it's the summer vacation eff=
et.

>
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> If I did something stupid, please tell me, as explained on that page.